In the processing of knitted fabrics, both tubular and open width, one of the important processing steps involves expanding the width of the fabric and compressing or compacting it in a lengthwise direction, so that the finished fabric is in a substantially relaxed and normalized state, as free as practicable of residual shrinkage or growth that could significantly effect the shape and size of finished garments made therefrom. During normal processing, and particularly when wet, knitted fabric is geometrically unstable and tends to become stretched and elongated in the lengthwise direction and correspondingly narrowed in width. Spreading and compacting are thus typically performed as finishing operations, in order to eliminate the severe distortions that occur during earlier processing.
In the Milligan et al. U.S. Pat. No. 5,016,329, an advantageous form of compressive shrinkage apparatus is described, which comprises opposed feeding and retarding rollers mounted for controlled rotation on spaced, parallel axes. These axes form a reference plane which extends between the two rollers at their point of closest approach, where the surfaces of the rollers are spaced apart by a short distance, for example about a 1/4 of an inch. An entry side confining shoe, with a blade extension at its discharge or downstream edge, is disposed about a portion of the feed roller surface, for example about 90.degree. C., and serves to confine fabric over its entire width, as the fabric is advanced by the feed roller toward a compressive shrinkage zone located substantially at the before mentioned reference plane. An exit side confining surface conforms to a portion of the surface of the retarding roller, and has a blade-like extension projecting substantially to the reference plane and confronting the entry side blade extension. The end surfaces of the respective blade extensions are disposed at an angle to the reference plane, such that fabric conveyed by the feeding roller is diverted sharply from the surface thereof and is directed into and through a compressive shrinkage zone defined by confronting surfaces of the respective blade extensions.
As the fabric emerges from the shrinkage zone, it immediately contacts the surface of the retarding roller, and is confined against such surface, by conforming portions of the exit side confining surface. The respective feeding and retarding rollers are separately controllably driven, such that the fabric is advanced toward and into the compressive shrinkage zone at one predetermined speed, and is conveyed away from the discharge side of said zone at a controllably lower speed by the retarding roller. As described in the before mentioned patents, lengthwise compressive shrinkage of the fabric is efficiently accomplished within a short compressive shrinkage zone defined by the angled, confronting surfaces of the respective blade extensions.
As can be appreciated, accurate adjustment of the positioning and relationship of the respective blade-like extensions with respect to each other and with respect to the driven rollers, particularly the feed roller, is critically important to uniform, high quality results in the compressive shrinkage operation. Of particular importance in this respect is the spacing between confronting surfaces of the respective blade-like extensions, which defines the thickness of the compressive shrinkage zone, and clearance spacing between the uppermost tip of the exit side blade-like extension and the surface of the feed roller.
One advantageous feature of the new apparatus includes a simplified and reliable, yet wholly foolproof mechanism to enable production operators of the equipment to make necessary adjustments of blade positioning, while at the same time preventing excess adjustment, such as might cause direct contact between a blade and an adjacent roller. In this respect, such contact, particularly when the equipment is in motion, can cause severe damage to the blades, and in many cases the rollers as well, resulting in expensive repairs and substantial downtime of the equipment. The described mechanism permits and enables non-technically skilled production operators to adjust the equipment only within predetermined limits which prevent damaging contact and which are substantially fail-safe even against operator abuse. To this end, for the critical adjustments required, primary and secondary adjustment means are provided. The primary adjustment means are accessible to and intended to be manipulated only by skilled technical personnel during machine setup and/or maintenance, being otherwise normally fixed. Secondary adjustment is provided by means of rotatable eccentric shafts. The shafts are designed and intended for rotation through a limited angle, for example 80.degree. or 90.degree. C., intended to provide sufficient adjustment to accommodate normal day-to-day variation in fabric types etc. Moreover, the eccentric shaft means are so arranged that the maximum possible adjustment in a "closing" direction, even if the shafts are improperly rotated throughout a greater angle than intended, is limited so as to avoid damage to the equipment.
In the operation of the compressive shrinkage apparatus described above, over a long period of time, can result in accumulations of stray fibers and the like, which may degrade performance. Accordingly, periodic cleaning of the machine is desirable, particularly when changing the line from one fabric type to another. In the new apparatus, there is advantageously incorporated in the adjusting mechanisms described above in-line fluid actuator devices which, in one position, constitute an integral and effectively fixed part of the adjusting mechanism but which can be actuated, when desired, to quickly move the respective entry side and exit side blade elements to open positions, well spaced from the respective feeding and retarding rollers. In these wide open positions, the equipment can be cleaned swiftly and efficiently by the use of an air hose, for example. In the past, such cleaning has been difficult and time consuming, in many cases involving undesired readjustment of the machine settings. The system of the invention, which provides for expedited cleaning, includes safety control facilities which in the first instance enable operation only when the machine is stopped and, in the second instance, assure that elements of the equipment are opened to their respective cleaning positions in a predetermined sequence, assuring that there is no unintended contact that could result in damage to delicate parts.
For a more complete understanding of the above and other features and advantages of the invention, reference should be made to the following detailed description of a preferred embodiment of the invention and to the accompanying drawings.